The invention relates generally to photo imaging on nonplanar substrates, and more particularly, to an imaging system for reflecting a two dimensional image onto a spherical semiconductor substrate.
Conventional integrated circuits, or "chips," are formed from two dimensional or flat surface semiconductor wafers. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to an integrated circuit fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface using various integrated circuit design and fabrication methods, such as very large scale integration ("VLSI") methods. Although the processed chip includes several layers fabricated thereon, the chip remains relatively flat.
A problem associated with modern integrated circuit fabrication facilities for flat chips is that they require extensive and expensive equipment. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from defecting and warping. Also, these types of fabrication facilities suffer from a relatively inefficient throughput as well as an inefficient use of the silicon. For example, facilities using in-batch manufacturing, where the wafers are processed by lots, must maintain huge inventories to efficiently utilize all the equipment of the facility.
U.S. Pat. No. 5,955,776 entitled SPHERICAL SURFACE SEMICONDUCTOR INTEGRATED CIRCUIT, herein incorporated by reference as if produced in its entirety, describes a three dimensional, spherical-shaped substrate for receiving various circuits. Of the many process disclosed in the above-referenced application, several are related to imaging a circuit design onto the three dimensional substrate. Often, the circuit design to be imaged may be two dimensional in nature.
There are numerous problems associated with applying a two-dimensional circuit design to a three-dimensional object, such as a sphere. Specifically, very large scale integrated ("VLSI") circuit designs for flat chips are achieved by using two dimensional based computer aided circuit design tools. However, these conventional methods of VLSI circuit design are not suitable for three-dimensional surfaces because modifying a two dimensional design to fit onto a three-dimensional curved surface results in several problems. For one, a two-dimensional design element, such as a line or shape, is deformed when fitted over a three-dimensional curved surface. This deformation results in distortion of the circuit design, which results in undesirable integrated circuit performance. Another problem is that in two dimensional VLSI circuit design, square and/or rectangular design units are used to modularize the design for ready transformation onto a two-dimensional surface. However, these conventional units do not fit properly onto a curved surface, such as a sphere, especially at the outermost edges of the design units, resulting in an inefficient use of the spherical surface of the semiconductor.
Therefore, what is needed is a system and a method of projecting a two-dimensional image onto a three-dimensional object, such as a sphere, using a reflective system with a plurality of mirrors that substantially eliminates errors caused by misalignment of the connections between neighboring projected images.